PERFORMANCE OF AUTOMOBILE
The pressure developed by the burning of fuel in the engine cylinder is transmitted to the crankshaft by the piston and connecting rod and a turning force or effort known as torque is produced. The crankshaft is coupled to the driving road wheels through clutch, gear box, propeller shaft, differential and axle shafts in an automobile. Thus, torque produced by the engine is transmitted through the drive line to the road wheels to propel the vehicle. The torque depends upon the pressure exerted on the piston and the length of crank arm and it is measured in newton- metre (N-m). The actual power delivered by the engine is known as brake power (B.P .) and it is measured in watts (W) or kilowatts (kW).
The pressure developed by the burning of fuel in the engine cylinder is transmitted to the crankshaft by the piston and connecting rod and a turning force or effort known as torque is produced. The crankshaft is coupled to the driving road wheels through clutch, gear box, propeller shaft, differential and axle shafts in an automobile. Thus, torque produced by the engine is transmitted through the drive line to the road wheels to propel the vehicle. The torque depends upon the pressure exerted on the piston and the length of crank arm and it is measured in newton- metre (N-m). The actual power delivered by the engine is known as brake power (B.P .) and it is measured in watts (W) or kilowatts (kW).
The torque increases with the increase in engine speed up to a certain point after which it starts to fall down even though the engine speed continues to increase. The numbers of revolution per minute (r.p.m.) at which the torque begins to decrease, depends upon the engine design. At higher speeds, engine vacuum falls down and less fuel enters the cylinder resulting in lesser force available at the piston and this there in a fall in torque. The power and torque curve of a particular petrol engine with respect to engine speed is shown in below figure:-
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| Torque and Engine Speed |
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